This class is a byte input stream with an associated MessageDigest object. When bytes are read with any of the read( ) methods, those bytes are automatically passed to the update( ) method of the MessageDigest. When you have finished reading bytes, you can call the digest( ) method of the MessageDigest to obtain a message digest. If you want to compute a digest just for some of the bytes read from the stream, use on( ) to turn the digesting function on and off. Digesting is on by default; call on(false) to turn it off. See also DigestOutputStream and MessageDigest.

Figure 14-8. java.security.DigestInputStream

public class DigestInputStream extends java.io.FilterInputStream {
// Public Constructors
     public DigestInputStream(java.io.InputStream stream, MessageDigest digest);
// Public Instance Methods
     public MessageDigest getMessageDigest( );  
     public void on(boolean on);  
     public void setMessageDigest(MessageDigest digest);  
// Public Methods Overriding FilterInputStream
     public int read( ) throws java.io.IOException;  
     public int read(byte[ ] b, int off, int len) throws java.io.IOException;  
// Public Methods Overriding Object
     public String toString( );  
// Protected Instance Fields
     protected MessageDigest digest;  
}